A thermostable trypsin inhibitor with antiproliferative activity from small pinto beans

J Enzyme Inhib Med Chem. 2014 Aug;29(4):485-90. doi: 10.3109/14756366.2013.805756. Epub 2013 Jul 16.


Small pinto bean is a cultivar of Phaseolus vulgaris. It produces a 16-kDa trypsin inhibitor that could be purified using anion exchange and size chromatography. Q-Sepharose, Mono Q and Superdex 75 columns were employed for the isolation process. Small pinto bean trypsin inhibitor demonstrated moderate pH stability (pH 2-10) and marked heat stability, with its trypsin inhibitory activity largely retained after exposure to 100 °C for half an hour. The activity was abolished in the presence of dithiothreitol, in a dose-dependent manner, implying that disulfide bonds in small pinto bean trypsin inhibitor are crucial for the activity. The trypsin inhibitor showed a blocked N-terminus. The trypsin inhibitor only slightly inhibited the viability of breast cancer MCF7 and hepatoma HepG2 cells at 125 μM.

Keywords: Bowman--Birk; Phaseolus vulgaris; dithiothreitol; leguminous.

MeSH terms

  • Cell Proliferation / drug effects
  • Cell Survival / drug effects
  • Dose-Response Relationship, Drug
  • Drug Screening Assays, Antitumor
  • Hep G2 Cells
  • Humans
  • MCF-7 Cells
  • Phaseolus / chemistry*
  • Seeds / chemistry*
  • Structure-Activity Relationship
  • Temperature*
  • Trypsin / metabolism*
  • Trypsin Inhibitors / chemistry
  • Trypsin Inhibitors / isolation & purification
  • Trypsin Inhibitors / pharmacology*


  • Trypsin Inhibitors
  • Trypsin